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Add special addressing functions for X, Y, N, etc

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This commit is contained in:
Joshua Goins 2022-03-29 22:55:57 -04:00
parent 5d82b8ee40
commit 67b3e37c72
1 changed files with 63 additions and 44 deletions
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107
src/emu.cpp
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@ -32,6 +32,31 @@ void EmulatorState::reset() {
draw_dirty = true; draw_dirty = true;
} }
// reads 0x0NNN
uint16_t readAddress(const uint16_t opcode) {
return opcode & 0x0fff;
}
// reads 0x00NN
uint8_t readNN(const uint16_t opcode) {
return opcode & 0x00ff;
}
// reads 0x000N
uint8_t readN(const uint16_t opcode) {
return (opcode & 0x000f);
}
// reads 0x0X00
uint8_t readX(const uint16_t opcode) {
return (opcode & 0x0f00) >> 8;
}
// reads 0x00Y0
uint8_t readY(const uint16_t opcode) {
return (opcode & 0x00f0) >> 4;
}
typedef void (*cpu_func)(const uint16_t opcode); typedef void (*cpu_func)(const uint16_t opcode);
void null_func(const uint16_t opcode) { void null_func(const uint16_t opcode) {
@ -91,24 +116,23 @@ void operation0(const uint16_t opcode) {
// 1NNN // 1NNN
void operation1(const uint16_t opcode) { void operation1(const uint16_t opcode) {
const uint16_t nnn = opcode & 0x0fff; const auto nnn = readAddress(opcode);
state.PC = nnn; state.PC = nnn;
} }
// 2NNN // 2NNN
void operation2(const uint16_t opcode) { void operation2(const uint16_t opcode) {
const uint16_t nnn = opcode & 0x0fff; const auto nnn = readAddress(opcode);
state.stack[state.stack_pointer] = state.PC; state.stack[state.stack_pointer++] = state.PC;
state.stack_pointer++;
state.PC = nnn; state.PC = nnn;
} }
// 3XNN // 3XNN
void operation3(const uint16_t opcode) { void operation3(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t nn = opcode & 0x00ff; const auto nn = readNN(opcode);
if(state.v[x] == nn) if(state.v[x] == nn)
state.PC += 4; state.PC += 4;
@ -118,8 +142,8 @@ void operation3(const uint16_t opcode) {
// 4XNN // 4XNN
void operation4(const uint16_t opcode) { void operation4(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t nn = opcode & 0x00ff; const auto nn = readNN(opcode);
if(state.v[x] != nn) if(state.v[x] != nn)
state.PC += 4; state.PC += 4;
@ -129,28 +153,26 @@ void operation4(const uint16_t opcode) {
// 6XNN // 6XNN
void operation6(const uint16_t opcode) { void operation6(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t nn = opcode & 0x00ff; const auto nn = readNN(opcode);
state.v[x] = nn; state.v[x] = nn;
state.PC += 2; state.PC += 2;
} }
// &XNN // &XNN
void operation7(const uint16_t opcode) { void operation7(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t nn = opcode & 0x00ff; const auto nn = readNN(opcode);
state.v[x] += nn; state.v[x] += nn;
state.PC += 2; state.PC += 2;
} }
// 8XY0 // 8XY0
void op8_func0(const uint16_t opcode) { void op8_func0(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
state.v[x] = state.v[y]; state.v[x] = state.v[y];
state.PC += 2; state.PC += 2;
@ -158,8 +180,8 @@ void op8_func0(const uint16_t opcode) {
// 8XY1 // 8XY1
void op8_func2(const uint16_t opcode) { void op8_func2(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
state.v[x] = state.v[x] & state.v[y]; state.v[x] = state.v[x] & state.v[y];
state.PC += 2; state.PC += 2;
@ -167,8 +189,8 @@ void op8_func2(const uint16_t opcode) {
// 8XY3 // 8XY3
void op8_func3(const uint16_t opcode) { void op8_func3(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
state.v[x] = state.v[x] ^ state.v[y]; state.v[x] = state.v[x] ^ state.v[y];
state.PC += 2; state.PC += 2;
@ -176,8 +198,8 @@ void op8_func3(const uint16_t opcode) {
// 8XY4 // 8XY4
void op8_func4(const uint16_t opcode) { void op8_func4(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
// TODO: implement tests // TODO: implement tests
if(state.v[y] < (0xFF - state.v[x])) if(state.v[y] < (0xFF - state.v[x]))
@ -191,8 +213,8 @@ void op8_func4(const uint16_t opcode) {
// 8XY5 // 8XY5
void op8_func5(const uint16_t opcode) { void op8_func5(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
// TODO: implement tests // TODO: implement tests
if(state.v[y] > state.v[x]) if(state.v[y] > state.v[x])
@ -206,7 +228,7 @@ void op8_func5(const uint16_t opcode) {
// 8XY6 // 8XY6
void op8_func6(const uint16_t opcode) { void op8_func6(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
state.v[0xF] = (state.v[x] & 1); state.v[0xF] = (state.v[x] & 1);
state.v[x] >>= 1; state.v[x] >>= 1;
@ -230,8 +252,8 @@ void operation8(const uint16_t opcode) {
// 9XY0 // 9XY0
void operation9(const uint16_t opcode) { void operation9(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
if(state.v[x] != state.v[y]) if(state.v[x] != state.v[y])
state.PC += 4; state.PC += 4;
@ -241,7 +263,7 @@ void operation9(const uint16_t opcode) {
// ANNN // ANNN
void operationA(const uint16_t opcode) { void operationA(const uint16_t opcode) {
const uint16_t nnn = opcode & 0x0fff; const auto nnn = readAddress(opcode);
state.I = nnn; state.I = nnn;
state.PC += 2; state.PC += 2;
@ -249,8 +271,8 @@ void operationA(const uint16_t opcode) {
// CXNN // CXNN
void operationC(const uint16_t opcode) { void operationC(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t nn = opcode & 0x00ff; const auto nn = readNN(opcode);
srand(time(nullptr)); srand(time(nullptr));
state.v[x] = (rand() % 0xFF) & nn; state.v[x] = (rand() % 0xFF) & nn;
@ -259,9 +281,9 @@ void operationC(const uint16_t opcode) {
// DXYN // DXYN
void operationD(const uint16_t opcode) { void operationD(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
const uint8_t y = (opcode & 0x00f0) >> 4; const auto y = readY(opcode);
const uint8_t n = opcode & 0x000f; const auto n = readN(opcode);
const uint8_t x_pos = state.v[x]; const uint8_t x_pos = state.v[x];
const uint8_t y_pos = state.v[y]; const uint8_t y_pos = state.v[y];
@ -295,7 +317,7 @@ void operationD(const uint16_t opcode) {
// EX9E & EXA1 // EX9E & EXA1
void operationE(const uint16_t opcode) { void operationE(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
switch(opcode & 0x00ff) { switch(opcode & 0x00ff) {
case 0x9E: case 0x9E:
@ -319,7 +341,7 @@ void operationE(const uint16_t opcode) {
// FX07 // FX07
void opF_func7(const uint16_t opcode) { void opF_func7(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
state.v[x] = state.delay_timer; state.v[x] = state.delay_timer;
@ -328,7 +350,7 @@ void opF_func7(const uint16_t opcode) {
// FX0A // FX0A
void opF_funcA(const uint16_t opcode) { void opF_funcA(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
for(int i = 0; i < 16; i++) { for(int i = 0; i < 16; i++) {
if(state.keys[i] != 0) { if(state.keys[i] != 0) {
@ -340,7 +362,7 @@ void opF_funcA(const uint16_t opcode) {
// FX55/FX65 & FX15 // FX55/FX65 & FX15
void opF_func5(const uint16_t opcode) { void opF_func5(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
switch((opcode & 0x00F0) >> 4) { switch((opcode & 0x00F0) >> 4) {
case 0x6: case 0x6:
@ -377,25 +399,23 @@ void opF_func5(const uint16_t opcode) {
// FX18 // FX18
void opF_func8(const uint16_t opcode) { void opF_func8(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
state.sound_timer = state.v[x]; state.sound_timer = state.v[x];
state.PC += 2; state.PC += 2;
} }
// FX29 // FX29
void opF_func9(const uint16_t opcode) { void opF_func9(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
state.I = state.v[x] * 0x5; state.I = state.v[x] * 0x5;
state.PC += 2; state.PC += 2;
} }
// FX1E // FX1E
void opF_funcE(const uint16_t opcode) { void opF_funcE(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
if((state.I + state.v[x]) > 0xFFF) if((state.I + state.v[x]) > 0xFFF)
state.v[15] = 1; state.v[15] = 1;
@ -403,13 +423,12 @@ void opF_funcE(const uint16_t opcode) {
state.v[15] = 0; state.v[15] = 0;
state.I += state.v[x]; state.I += state.v[x];
state.PC += 2; state.PC += 2;
} }
// FX33 // FX33
void opF_func3(const uint16_t opcode) { void opF_func3(const uint16_t opcode) {
const uint8_t x = (opcode & 0x0f00) >> 8; const auto x = readX(opcode);
int decimal_rep = state.v[x]; int decimal_rep = state.v[x];